Irons and woods are two major kinds of golf club. Generally speaking, irons are designed for accuracy and woods can create distance. Nowadays, although the modern "wood-club" is substantially made of metal or alloy instead of wood, it is still traditionally called wood-club.
Hollow metallic golf club wood heads are well known in arts as disclosed in U.S. Pat. Nos. 5,429,357, 5,460,371, and 5,485,998. The conventional hollow metallic golf club head 10 of the so-called "wood" head type, as shown in FIG. 1, comprises a planar face member 11, a rear shell member 12 having a connecting tube 121 integrally, upwardly and inclinedly extended from a side thereof for combining together with a hosel 13. The rear shell member 12 contributes the major weight of the club head 10 for providing a steady swing. The inclined angle between the connecting tube 121 and the rear shell member 12 determined the lie angle of the club head. The face member 11 is the most important element of the club head 10 because it is the substantial part hitting the golf ball. The loft angle of the face member 11 determines the height and distance of the golf ball to be driven. The face member 11 also forms the impact plane that should be aligned in predetermined angle with the golf shaft 14.
Driver and the fairway woods including such as 3-wood, 5-wood and 7-wood, each having a different loft angle and different shaft length, are the most common wood clubs in your golf bag. In 1915, Alex Smith won the Metropolitan Open, then a very important event, with a driver 48 inches long. Power comes from the length of the club shaft and the hitting force. Therefore, the longer of the club shaft and the smaller of the loft angle of a wood club can hit the golf ball farther for more distance.
As mentioned above, the longer the club shaft, generally enables the wood-club head to hit a ball farther. However, it is nearly impossible to have two persons having exactly the same height and the length of bands and legs. In other words, the body structure of everybody is different but all of them have to adopt the limited manufacturing sizes and shapes of the wood club. Practically, the length of a club shaft must match the distance between the user's hands and the ground. A shorter golf player such as Asian should uses a shorter club shaft in order to provide a perfect lie angle and generate a natural and solid swing but also limiting the distance.
As shown in FIG. 5A, when a golf player having a specific height and arm length sets a wood-club with matching shaft length, the club head should be naturally lie on ground corresponding to the constant lie angle of the golf club. If another wood-club having just one inch longer shaft length is used (as illustrated in dotted lines in FIG. 5A), the club head is then unable to be addressed at the correct lie angle without changing the natural setting of the player. In other words, if a shorter golf player would like to use a longer club to create more distance, he or she must absorb the risk of having non-natural swings.
Besides, due to the structure of the conventional wood-club head as shown in FIGS. 1 and 5A, the loft angle and lie angle of the club head 10 are constant and unadjustable, so that the different users must adjust their bodies, settings and swings to adapt the particular club head 10.
Moreover, the vibration and shock produced when the club head hits the golf ball will partially be absorbed by the club head and mainly be transferred to the golf shaft and be absorbed by the player's hands, arms and shoulders. That is why the manufacturers recently implant foaming material inside the golf shaft for helping to absorb some of shock and vibration. In fact, in order to minimize the sport injuries to the players, any structure improvement that can reduce the vibration and shock being transferred to the player is good design.